Slime Mold

Written by Joshua Pringle

During late July and early August, patches of a brown, crusty substance began to form periodically overnight on our mulch (which the landscapers had laid everywhere, including over the stone path I built, but that’s another story). Some questions began to form: was it something the landscapers were spraying? Was it a vomit/fungus hybrid invasion? Thanks to the wonders of Google (my supervisor says “you just need to know how to word your question”), we learned that it is something known officially as “Fuligo septica”. Unofficially, it is colorfully known as “dog vomit slime mold” or “scrambled egg fungus”.

Slime molds are saprophytic, which means that they feed on decaying organic materials. They form structures called plasmodia which are masses that can move and engulf food like amoebas can. (Interestingly, this differs from the eating habits of a fungus, because fungi digest their food with exoenzymes first, before ingesting it). Our Fuligo septica then converts into a relatively large (for a slime mold) cushion of spores enclosed by an outer wall called a peridium.

The mold is broken up easily and we simply scraped it away even though it won’t harm our plants. It is most likely to show up during warm, wet periods and often grows in wood mulches or on the sides of untreated wood, and sometimes in lawn grass.

Slime molds produce spores that are wind-borne. They are very resistant, and can survive even during hot, dry weather. The spores can remain viable for several years, waiting for conditions to be right.

Slime molds have also inspired a science fiction movie, “The Blob.” (1958 with Steve McQueen, remade in 1988). According to imdb, it’s about “A mysterious creature from another planet, resembling a giant blob of jelly, lands on earth. The people of a nearby small town refuse to listen to some teenagers who have witnessed the blob’s destructive power. In the meantime, the blob just keeps on getting bigger.”